槲皮黄素-3-α-阿拉伯糖苷胁迫下内生真菌对木麻黄幼苗根系形态和生理特性的影响

Effects of endophyte fungi on the morphological and physiological characteristics of Casuarina equisetifolia seedling roots under quercetin-3-α-arabinoside stress

采用水培方式研究不同浓度化感物质槲皮黄素-3-α-阿拉伯糖苷（Q3A）胁迫对感染（EI）和未感染（EF）内生真菌的木麻黄幼苗根系形态和生理特性的影响.结果显示：不同浓度Q3A胁迫下,感染内生真菌能够有限缓解化感物质的胁迫,在中轻度胁迫（50、25、12.5 mg/L）下有明显的效果,表现在与木麻黄EF相比,木麻黄EI根系生物量、根系总长、根表面积显著增加;根系活力显著提升,根系渗透调节物质除可溶性蛋白含量显著增加外,可溶性糖、游离脯氨酸含量显著降低;根系抗氧化系统除谷胱甘肽还原酶（GR）活性显著降低,超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、愈创木酚过氧化物酶（GPX）、抗坏血酸过氧化物酶（APX）、还原型抗坏血酸（AsA）和还原型谷胱甘肽（GSH）含量均能显著增强;过氧化氢（H2O2）、羟自由基（OH·）含量、超氧阴离子（O2^-）产生速率和膜脂过氧化产物丙二醛（MDA）含量也显著降低;内生真菌缓解化感物质胁迫的有效浓度与木麻黄根系能够耐受的化感物质胁迫浓度存在一定相似性.上述研究表明内生真菌能在一定条件下缓解不同浓度化感物质槲皮黄素-3-α-阿拉伯糖苷胁迫对木麻黄幼苗根系生长的抑制和氧化损伤,提升木麻黄根系的抗逆性,在木麻黄根系适应化感胁迫的调节中起关键作用.

The effects of different concentrations of quercetin-3-α-arabinoside（Q3 A） on the root morphology and physiological characteristics of Casuarina equisetifolia seedlings infected（EI） and not infected（EF） with endophytic fungi were determined by hydroponics. The results showed that endophytic fungi could alleviate the allelochemical stress from different concentrations of Q3 A, with significant effects under slight allelochemical stress（50, 25, and 12.5 mg/L）. Compared with EF, the root biomass, root length, root surface area, and root activity of EI significantly increased, and the contents of soluble sugar and free proline in root osmotic adjustment substances significantly decreased. Endophyte infection significantly decreased the activity of glutathione reductase, and the activities of protective enzymes such as superoxide dismutase, catalase, guaiacol peroxidase, and ascorbate peroxidase APX, As A, and GSH were significantly increased. The H2O2 and OH· contents, production rate of O2^-, and malondialdehyde content were all significantly reduced. Therefore, the effective concentrations of endophyte fungi alleviating allelochemical stress were similar to those of the allelopathic substances that the C. equisetifolia root system could tolerate. Thus, endophyte fungi can alleviate the inhibition of root growth and oxidative damage of C. equisetifolia seedlings under different concentrations of Q3 A stress, enhance the resistance of C. equisetifolia, and play a key role in the adaption of C. equisetifolia roots to allelochemical stress.